text: Inoculate a tube of glucose phosphate broth with a pure inoculum of test organism and incubate at 35 °C for 24 hours.
  To 1 mL of this broth add 0.6 mL of 5% α-Naphthol followed by 0.2 mL of 40% KOH. Shake the tube gently to expose the medium to atmospheric oxygen and allow the tube to remain undisturbed for 10–15 minutes.